Electromagnetic wave energy, such as radio frequency (RF) waves and light, has been widely used to transmit information-bearing signals, but can be easily intercepted. The prior art further includes the transmission of information bearing signals in the mode of sound waves (such as acoustic waves and ultrasonic waves), pressure waves, or other types of mechanical vibrations with piezoelectric transducers. Compared to electromagnetic wave energy, sound wave energy is optimal for signal transmission in certain environments. For example, sound wave can pass through a Faraday cage. Also, certain types of sound waves, such as ultrasonic waves and acoustic waves, have a very limited propagation range, and thus make the interception of signal outside such a short propagation range impossible. However, no optimal combination of both forms of communications has been established. Therefore, there is a long-felt need for circuits, systems and methods that utilize both electromagnetic wave and sound wave to receive and/or generate signals.
In addition, different sound wave transducing media have different characteristics. There is also a long-felt need for circuits, systems and methods that enable transmission of signals in the form of sound wave energy in a complex environment that is composed of multiple sound wave transducing media. The present invention is offered to meet these two stated objects and other objects that are made obvious in light of the present disclosure.